<?php
// This file should be in UTF8 without BOM - Accents examples: éèê
/*
 * Transparent SHA-256 Implementation for PHP 4 and PHP 5
 *
 * Author: Perry McGee (pmcgee@nanolink.ca)
 * Website: http://www.nanolink.ca/pub/sha256
 *
 * Copyright (C) 2006,2007,2008,2009 Nanolink Solutions
 *
 * Created: Feb 11, 2006
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation; either
 *    version 2.1 of the License, or (at your option) any later version.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.

 *    You should have received a copy of the GNU Lesser General Public
 *    License along with this library; if not, write to the Free Software
 *    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *    or see <http://www.gnu.org/licenses/>.
 *
 *  Include:
 *
 *   require_once("[path/]sha256.inc.php");
 *
 *  Usage Options:
 *
 *   1) $shaStr = hash('sha256', $string_to_hash);
 *
 *   2) $shaStr = sha256($string_to_hash[, bool ignore_php5_hash = false]);
 *
 *   3) $obj = new nanoSha2([bool $upper_case_output = false]);
 *      $shaStr = $obj->hash($string_to_hash[, bool $ignore_php5_hash = false]);
 *
 * Reference: http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html
 *
 * 2007-12-13: Cleaned up for initial public release
 * 2008-05-10: Moved all helper functions into a class.  API access unchanged.
 * 2009-06-23: Created abstraction of hash() routine
 * 2009-07-23: Added detection of 32 vs 64bit platform, and patches.
 *             Ability to define "_NANO_SHA2_UPPER" to yeild upper case hashes.
 * 2009-08-01: Added ability to attempt to use mhash() prior to running pure
 *             php code.
 *
 * NOTE: Some sporadic versions of PHP do not handle integer overflows the
 *       same as the majority of builds.  If you get hash results of:
 *        7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff7fffffff
 *
 *       If you do not have permissions to change PHP versions (if you did
 *       you'd probably upgrade to PHP 5 anyway) it is advised you install a
 *       module that will allow you to use their hashing routines, examples are:
 *       - mhash module : http://ca3.php.net/mhash
 *       - Suhosin : http://www.hardened-php.net/suhosin/
 *
 *       If you install the Suhosin module, this script will transparently
 *       use their routine and define the PHP routine as _nano_sha256().
 *
 *       If the mhash module is present, and $ignore_php5_hash = false the
 *       script will attempt to use the output from mhash prior to running
 *       the PHP code.
 */
if (!class_exists('nanoSha2')) {
	class nanoSha2 {
		// php 4 - 5 compatable class properties
		var $toUpper;
		var $platform;
		// Php 4 - 6 compatable constructor
		function nanoSha2($toUpper = false)
		{
			// Determine if the caller wants upper case or not.
			$this->toUpper = is_bool($toUpper)
			? $toUpper
			: ((defined('_NANO_SHA2_UPPER')) ? true : false);
			// Deteremine if the system is 32 or 64 bit.
			$tmpInt = (int)4294967295;
			$this->platform = ($tmpInt > 0) ? 64 : 32;
		}
		// Do the SHA-256 Padding routine (make input a multiple of 512 bits)
		function char_pad($str)
		{
			$tmpStr = $str;

			$l = strlen($tmpStr) * 8; // # of bits from input string

			$tmpStr .= "\x80"; // append the "1" bit followed by 7 0's

			$k = (512 - (($l + 8 + 64) % 512)) / 8; // # of 0 bytes to append
			$k += 4; // PHP Strings will never exceed (2^31)-1, 1st 32bits of
			// the 64-bit value representing $l can be all 0's
			for ($x = 0; $x < $k; $x++) {
				$tmpStr .= "\0";
			}
			// append the 32-bits representing # of bits from input string ($l)
			$tmpStr .= chr((($l >> 24) &0xFF));
			$tmpStr .= chr((($l >> 16) &0xFF));
			$tmpStr .= chr((($l >> 8) &0xFF));
			$tmpStr .= chr(($l &0xFF));

			return $tmpStr;
		}
		// Here are the bitwise and functions as defined in FIPS180-2 Standard
		function addmod2n($x, $y, $n = 4294967296) // Z = (X + Y) mod 2^32
		{
			$mask = 0x80000000;

			if ($x < 0) {
				$x &= 0x7FFFFFFF;
				$x = (float)$x + $mask;
			}

			if ($y < 0) {
				$y &= 0x7FFFFFFF;
				$y = (float)$y + $mask;
			}

			$r = $x + $y;

			if ($r >= $n) {
				while ($r >= $n) {
					$r -= $n;
				}
			}

			return (int)$r;
		}
		// Logical bitwise right shift (PHP default is arithmetic shift)
		function SHR($x, $n) // x >> n
		{
			if ($n >= 32) { // impose some limits to keep it 32-bit
				return (int)0;
			}

			if ($n <= 0) {
				return (int)$x;
			}

			$mask = 0x40000000;

			if ($x < 0) {
				$x &= 0x7FFFFFFF;
				$mask = $mask >> ($n-1);
				return ($x >> $n) | $mask;
			}

			return (int)$x >> (int)$n;
		}

		function ROTR($x, $n)
		{
			return (int)(($this->SHR($x, $n) | ($x << (32 - $n)) &0xFFFFFFFF));
		}
		function Ch($x, $y, $z)
		{
			return ($x &$y) ^ ((~$x) &$z);
		}
		function Maj($x, $y, $z)
		{
			return ($x &$y) ^ ($x &$z) ^ ($y &$z);
		}
		function Sigma0($x)
		{
			return (int) ($this->ROTR($x, 2) ^ $this->ROTR($x, 13) ^ $this->ROTR($x, 22));
		}
		function Sigma1($x)
		{
			return (int) ($this->ROTR($x, 6) ^ $this->ROTR($x, 11) ^ $this->ROTR($x, 25));
		}
		function sigma_0($x)
		{
			return (int) ($this->ROTR($x, 7) ^ $this->ROTR($x, 18) ^ $this->SHR($x, 3));
		}
		function sigma_1($x)
		{
			return (int) ($this->ROTR($x, 17) ^ $this->ROTR($x, 19) ^ $this->SHR($x, 10));
		}

		/*
         * Custom functions to provide PHP support
         */
		// split a byte-string into integer array values
		function int_split($input)
		{
			$l = strlen($input);

			if ($l <= 0) {
				return (int)0;
			}

			if (($l % 4) != 0) { // invalid input
				return false;
			}

			for ($i = 0; $i < $l; $i += 4) {
				$int_build = (ord($input[$i]) << 24);
				$int_build += (ord($input[$i + 1]) << 16);
				$int_build += (ord($input[$i + 2]) << 8);
				$int_build += (ord($input[$i + 3]));

				$result[] = $int_build;
			}

			return $result;
		}

		/**
		 * Process and return the hash.
		 *
		 * @param  $str Input string to hash
		 * @param  $ig_func Option param to ignore checking for php > 5.1.2
		 * @return string Hexadecimal representation of the message digest
		 */
		function hash($str, $ig_func = false)
		{
			unset($binStr); // binary representation of input string
			unset($hexStr); // 256-bit message digest in readable hex format

			// check for php's internal sha256 function, ignore if ig_func==true
			if ($ig_func == false) {
				if (function_exists('hash') && version_compare(PHP_VERSION, '5.1.2', '>=')) {
					return hash("sha256", $str, false);
				} elseif (function_exists('mhash') && defined('MHASH_SHA256')) {
					return base64_encode(bin2hex(mhash(MHASH_SHA256, $str)));
				}
			}

			/*
             * SHA-256 Constants
             *  Sequence of sixty-four constant 32-bit words representing the
             *  first thirty-two bits of the fractional parts of the cube roots
             *  of the first sixtyfour prime numbers.
             */
			$K = array((int)0x428a2f98, (int)0x71374491, (int)0xb5c0fbcf,
				(int)0xe9b5dba5, (int)0x3956c25b, (int)0x59f111f1,
				(int)0x923f82a4, (int)0xab1c5ed5, (int)0xd807aa98,
				(int)0x12835b01, (int)0x243185be, (int)0x550c7dc3,
				(int)0x72be5d74, (int)0x80deb1fe, (int)0x9bdc06a7,
				(int)0xc19bf174, (int)0xe49b69c1, (int)0xefbe4786,
				(int)0x0fc19dc6, (int)0x240ca1cc, (int)0x2de92c6f,
				(int)0x4a7484aa, (int)0x5cb0a9dc, (int)0x76f988da,
				(int)0x983e5152, (int)0xa831c66d, (int)0xb00327c8,
				(int)0xbf597fc7, (int)0xc6e00bf3, (int)0xd5a79147,
				(int)0x06ca6351, (int)0x14292967, (int)0x27b70a85,
				(int)0x2e1b2138, (int)0x4d2c6dfc, (int)0x53380d13,
				(int)0x650a7354, (int)0x766a0abb, (int)0x81c2c92e,
				(int)0x92722c85, (int)0xa2bfe8a1, (int)0xa81a664b,
				(int)0xc24b8b70, (int)0xc76c51a3, (int)0xd192e819,
				(int)0xd6990624, (int)0xf40e3585, (int)0x106aa070,
				(int)0x19a4c116, (int)0x1e376c08, (int)0x2748774c,
				(int)0x34b0bcb5, (int)0x391c0cb3, (int)0x4ed8aa4a,
				(int)0x5b9cca4f, (int)0x682e6ff3, (int)0x748f82ee,
				(int)0x78a5636f, (int)0x84c87814, (int)0x8cc70208,
				(int)0x90befffa, (int)0xa4506ceb, (int)0xbef9a3f7,
				(int)0xc67178f2);
			// Pre-processing: Padding the string
			$binStr = $this->char_pad($str);
			// Parsing the Padded Message (Break into N 512-bit blocks)
			$M = str_split($binStr, 64);
			// Set the initial hash values
			$h[0] = (int)0x6a09e667;
			$h[1] = (int)0xbb67ae85;
			$h[2] = (int)0x3c6ef372;
			$h[3] = (int)0xa54ff53a;
			$h[4] = (int)0x510e527f;
			$h[5] = (int)0x9b05688c;
			$h[6] = (int)0x1f83d9ab;
			$h[7] = (int)0x5be0cd19;
			// loop through message blocks and compute hash. ( For i=1 to N : )
			$N = count($M);
			for ($i = 0; $i < $N; $i++) {
				// Break input block into 16 32bit words (message schedule prep)
				$MI = $this->int_split($M[$i]);
				// Initialize working variables
				$_a = (int)$h[0];
				$_b = (int)$h[1];
				$_c = (int)$h[2];
				$_d = (int)$h[3];
				$_e = (int)$h[4];
				$_f = (int)$h[5];
				$_g = (int)$h[6];
				$_h = (int)$h[7];
				unset($_s0);
				unset($_s1);
				unset($_T1);
				unset($_T2);
				$W = array();
				// Compute the hash and update
				for ($t = 0; $t < 16; $t++) {
					// Prepare the first 16 message schedule values as we loop
					$W[$t] = $MI[$t];
					// Compute hash
					$_T1 = $this->addmod2n($this->addmod2n($this->addmod2n($this->addmod2n($_h, $this->Sigma1($_e)), $this->Ch($_e, $_f, $_g)), $K[$t]), $W[$t]);
					$_T2 = $this->addmod2n($this->Sigma0($_a), $this->Maj($_a, $_b, $_c));
					// Update working variables
					$_h = $_g;
					$_g = $_f;
					$_f = $_e;
					$_e = $this->addmod2n($_d, $_T1);
					$_d = $_c;
					$_c = $_b;
					$_b = $_a;
					$_a = $this->addmod2n($_T1, $_T2);
				}

				for (; $t < 64; $t++) {
					// Continue building the message schedule as we loop
					$_s0 = $W[($t + 1)&0x0F];
					$_s0 = $this->sigma_0($_s0);
					$_s1 = $W[($t + 14)&0x0F];
					$_s1 = $this->sigma_1($_s1);

					$W[$t&0xF] = $this->addmod2n($this->addmod2n($this->addmod2n($W[$t&0xF], $_s0), $_s1), $W[($t + 9)&0x0F]);
					// Compute hash
					$_T1 = $this->addmod2n($this->addmod2n($this->addmod2n($this->addmod2n($_h, $this->Sigma1($_e)), $this->Ch($_e, $_f, $_g)), $K[$t]), $W[$t&0xF]);
					$_T2 = $this->addmod2n($this->Sigma0($_a), $this->Maj($_a, $_b, $_c));
					// Update working variables
					$_h = $_g;
					$_g = $_f;
					$_f = $_e;
					$_e = $this->addmod2n($_d, $_T1);
					$_d = $_c;
					$_c = $_b;
					$_b = $_a;
					$_a = $this->addmod2n($_T1, $_T2);
				}

				$h[0] = $this->addmod2n($h[0], $_a);
				$h[1] = $this->addmod2n($h[1], $_b);
				$h[2] = $this->addmod2n($h[2], $_c);
				$h[3] = $this->addmod2n($h[3], $_d);
				$h[4] = $this->addmod2n($h[4], $_e);
				$h[5] = $this->addmod2n($h[5], $_f);
				$h[6] = $this->addmod2n($h[6], $_g);
				$h[7] = $this->addmod2n($h[7], $_h);
			}
			// Convert the 32-bit words into human readable hexadecimal format.
			$hexStr = sprintf("%08x%08x%08x%08x%08x%08x%08x%08x", $h[0], $h[1], $h[2], $h[3], $h[4], $h[5], $h[6], $h[7]);

			return ($this->toUpper) ? strtoupper($hexStr) : $hexStr;
		}
	}
}

if (!function_exists('str_split')) {
	/**
	 * Splits a string into an array of strings with specified length.
	 * Compatability with older verions of PHP
	 */
	function str_split($string, $split_length = 1)
	{
		$sign = ($split_length < 0) ? -1 : 1;
		$strlen = strlen($string);
		$split_length = abs($split_length);

		if (($split_length == 0) || ($strlen == 0)) {
			$result = false;
		} elseif ($split_length >= $strlen) {
			$result[] = $string;
		} else {
			$length = $split_length;

			for ($i = 0; $i < $strlen; $i++) {
				$i = (($sign < 0) ? $i + $length : $i);
				$result[] = substr($string, $sign * $i, $length);
				$i--;
				$i = (($sign < 0) ? $i : $i + $length);

				$length = (($i + $split_length) > $strlen)
				? ($strlen - ($i + 1))
				: $split_length;
			}
		}

		return $result;
	}
}

/**
 * Main routine called from an application using this include.
 *
 * General usage:
 *    require_once('sha256.inc.php');
 *    $hashstr = sha256('abc');
 *
 * Note:
 * PHP Strings are limitd to (2^31)-1, so it is not worth it to
 * check for input strings > 2^64 as the FIPS180-2 defines.
 */
// 2009-07-23: Added check for function as the Suhosin plugin adds this routine.
if (!function_exists('sha256')) {
	/**
	 * sha256()
	 *
	 * @param mixed $str
	 * @param boolean $ig_func
	 * @return
	 */
	function sha256($str, $ig_func = false)
	{
		$obj = new nanoSha2((defined('_NANO_SHA2_UPPER')) ? true : false);
		return $obj->hash($str, $ig_func);
	}
} else {
	/**
	 * _nano_sha256()
	 *
	 * @param mixed $str
	 * @param boolean $ig_func
	 * @return
	 */
	function _nano_sha256($str, $ig_func = false)
	{
		$obj = new nanoSha2((defined('_NANO_SHA2_UPPER')) ? true : false);
		return $obj->hash($str, $ig_func);
	}
}

if (!function_exists('hash')) {
	/**
	 * support to give php < 5.1.2 the hash() routine which abstracts this code.
	 *
	 * @param mixed $algo
	 * @param mixed $data
	 * @return
	 */
	function hash($algo, $data)
	{
		if (empty($algo) || !is_string($algo) || !is_string($data)) {
			return false;
		}

		if (function_exists($algo)) {
			return $algo($data);
		}
	}
}

